In current practice plasma or serum is typically separated from the red blood cells of a blood sample by placing whole liquid or clotted blood respectively, in a tube, placing the tube in a swinging bucket type centrifuge which upon activation rotates rapidly and causes the tube to acquire a horizontal position. The red cells being heavier than the plasma or serum migrate to the end of the tube furthest from the center of rotation thus producing separation of the various components of the sample.
The above procedure is time consuming requiring extended periods of centrifuging to achieve the desired results because of the long migration path of the red cells.
U.S. Pat. No. 3,190,547 to J. J. Shanley discloses in FIGS. 10-13 a centrifuge wherein bottles are located below evacuated plasma receivers. The combination of each bottle and receiver is rotated together with other such combinations about an axis parallel to the axis of each combination, which axis passes through a bottle and receiver. In consequence red cells migrate upon rotation of the bottles about such axis toward the outer walls of the sample bottles. Upon completion of centrifuging the sample bottle and plasma receivers are connected through hollow needles situated in self-sealing stoppers in each member of the combination. The plasma is drawn into the plasma receivers which are then spun at a higher than previous rotational velocity separately from the now stationary specimen bottles to produce further separation of the materials drawn therein.
The mechanism is very complex requiring two separately driven rotating shafts, two different hollow needles to affect interconnection of the bottle and the receiver, rectangular shaped or other non-cylindrical specimen bottles to ensure that the bottles do not rotate about their own axes. This procedure further requires proper registration of the needle with the sample bottle. To provide proper alignment with the various strata in the specimen bottle, a readily movable self-sealing stopper in the specimen bottle is employed to assist in the search for the strata of the material desired. This procedure may require opening of the specimen bottle to locate the strata interface thus compromising the sterility of the specimen and possibly endangering the workers.